Sha Ai-min

Study of image-based pavement cracking measurement techniques

Cracking is one of the most common diseases that happen to the pavement and a field cracking survey and a forensic investigation are important work for preventive maintenance. In order to measure the pavement crackings automatically, this paper uses digital image processing techniques to process the pavement cracking images acquired by the digital camera and classify the pavement cracking types according to the topological properties to line crackings and alligator cracking, then classify the line crackings to longitudinal and transverse cracking according to the chain code of the cracking in the image. At the same time, the paper calculates the length and width of the line crackings and the area of the box rectangle of the alligator cracking. Finally, the paper calculates the Cracking Index (CI) of the pavement.

Research on Relationship between Aging State and Low-Temperature Performance of Asphalt Mixture

Aging phenomenon of asphalt material exists in the course of mixing, spreading, and rolling of asphalt mixture, as well as the use in the asphalt pavement. The indirect tensile strength test was used to evaluate the performance of asphalt mixtures at low-temperature under different aging conditions. As compared with the results from the original short-term aging and the long-term aging asphalt mixtures, the results show that the original asphalt mixture cannot reflect the real performance of the asphalt mixture in the field. The short-term aging specimens are more sensitive than long-term aging specimens in evaluating the performance of the asphalt mixture at low temperature. Tests results also indicate that the consideration of aging during the evaluation of asphalt pavement performance is necessary.

Application of Chemical Grouting Method in Settle Down Disengaging of Cement Concrete Slab

For expressway cement concrete pavement bottom existing void problems, the paper introduced the method of chemical grouting treatment according to the analysis of the causes of the disease began. According to grouting material, devices selection, construction procedure, quality inspection, treatment effect, and the problems existing in the project and so on, this paper summarized treatment experience. The results showed that treating hole under Concrete Pavement with Chemical grouting method can improve pavement usefulness obviously.